1. Field of the Invention
The present invention relates generally to catheters having an expandable balloon and to premounted balloon expandable stent balloon catheters, and specifically to a dilatation balloon catheter with a balloon protector means or a stent delivery system with a balloon and stent protector means.
2. Description of Related Art
Percutaneous transluminal coronary ingioplasty (PTCA) is a procedure which is well established for the treatment of blockages in the coronary arteries. Blockages may occur from cholesterol precipitation on the coronary wall which may be in any stage from initial deposit through aged lesions. Coronary arteries may also become blocked due to formation of thrombus.
The most widely used form of percutaneous coronary angioplasty makes use of a dilatation balloon catheter. In typical PTCA procedures, the cardiovascular system of a patient is accessed with an introducer, usually in the groin area. All other devices including a guiding catheter are percutaneously introduced into the cardiovascular system of a patient through the introducer and advanced through a vessel until the distal end thereof is at a desired location in the vasculature. A guide wire and a dilatation catheter having a balloon on the distal end thereof are introduced through the guiding catheter with the guide wire sliding through the dilatation catheter. The guide wire is first advanced out of the guiding catheter into the patienit""s coronary vasculature and the dilatation catheter is advanced over the previously advanced guide wire until the dilatation balloon is properly positioned across the lesion. Once in position across the lesion, the flexible, expandable, preformed balloon is inflated to a predetermined size with a fluid at relatively high pressures, such as greater than about four atmospheres, to radially compress the atherosclerotic plaque of the lesion against the inside of the artery wall and thereby dilate the lumen of the artery. The balloon is then deflated to a small profile so that the dilatation catheter may be withdrawn from the patients vasculature and blood flow resumed through the dilated artery.
In angioplasty procedures of the kind described above, there may be restenosis of the artery, which either necessitates another angioplasty procedure, a surgical by-pass operation, or some method of repairing or strengthening the area. To reduce restenosis and strengthen the area, a physician can implant an intravascular prosthesis for maintaining vascular patency, called a stent, inside the artery at the lesion. In general, stents are prosthetic devices which can be positioned within a body cavity, for example, a blood vessel of the body of a living human or in some other difficulty accessible place. A stent generally has a diameter which may be increased or decreased. Stents are particularly useful for permanently widening a vessel which is in a narrowed state, or for internally supporting a vessel damaged by an aneurysm.
Such stents are typically introduced into the body cavity by use of a catheter. The catheter is usually of the balloon catheter type in which the balloon is utilized to expand the stent, which is positioned over the balloon, to place it in a selected location in the body cavity. The stent is expanded to a larger diameter for placement in the vasculature, often by the balloon portion of the catheter. Stents delivered to a restricted coronary artery, expanded to a larger diameter by a balloon catheter, and left in place in the artery at the site of a dilated lesion are shown in U.S. Pat. No. 4,740,207 to Kreamer and U.S. Pat. No. 5,007,926 to Derbyshire.
One important characteristic of a dilatation balloon catheter is its xe2x80x9cprofilexe2x80x9d, which is determined by the outer diameter (O.D.) of the distal end portion of the balloon and stent when deflated. The outer diameter affects the ease and ability of the dilatation catheter to pass through a guide catheter, through the coronary arteries, and across a tight lesion. Considerable effort has been made in developing low profile dilatation balloon catheters. U.S. Pat. No. 5,342,307, incorporated herein by reference, discloses a balloon protector sleeve used with a tri-fold dilatation balloon catheter for angioplasty.
Minimization of xe2x80x9cprofilexe2x80x9d is of importance in balloon catheters and stent delivery systems. Accordingly, the present invention is particularly directed to improved arrangements of balloon catheters having a balloon protector and stent delivery systems having a balloon and including a stent protector means which provide a minimized profile.
This invention concerns medical devices such as balloon catheters and apparatus suitable for delivery of stents to body cavities. The present invention is particularly directed to improved balloon protectors for use with balloon catheters and to improved arrangements for stent delivery systems, the improvements comprising stent protector means.
Accordingly, the present invention provides a catheter having an expandable distal portion constructed and arranged for expanding the outer diameter of the catheter from a contracted state to an expanded state. The distal portion of the catheter comprises a balloon which is folded or otherwise collapsed, and is expandable to an expanded condition. The balloon protector may comprise removable first and second sleeves. The first removable (inner) sleeve is positioned around the balloon, the inner sleeve being made of a lubricious material and further comprising a first end, a second end and a slit extending therethrough. The slit may extend from end to end. Alternatively, the slit may extend along a predetermined length of the sleeve, the rest of the length of the sleeve comprising a continuous tube. The slit provides a variable inner diameter to ease sliding the sleeve over the balloon. The second removable (outer) sleeve is positioned over the first (inner) sleeve, the outer sleeve having a constrictive relationship with the inner sleeve. The outer sleeve thereby provides an additional compressive force to reduce the profile of the constricted balloon. For example, the outer sleeve may have an inner diameter less than the outer diameter of the inner sleeve, whereby when compressed by the outer sleeve, the inner sleeve will have an inner diameter approximately equal to or greater than the profile of the balloon in its contracted state. The inner and outer sleeves are removed prior to use of the catheter.
Alternatively, the balloon protector means may comprise a single compressive sleeve. This single compressive sleeve may be of any configuration described herein. A preferred embodiment of the single sleeve has a slit along the length thereof. Another preferred embodiment of the single sleeve has a helical slit along a predetermined length of the sleeve, defining a spiral cut region and a continuous tubular region. Yet another preferred embodiment has a spiral cut region and a continuous tubular region, the continuous tubular region comprising a dimpled region and a straight tubular region. The dimples may be round-like, spiral, triangular, oval, oblong, circular (like tire treads) around the circumference or at an angle around the circumference, or combinations thereof. The dimples may also be of any other suitable configuration. In another alternative embodiment, the single sleeve may comprise a dimpled region extending along part of the single sleeve or the entire sleeve.
The present invention also provides a catheter having an expandable distal portion constructed and arranged for expanding the outer diameter of the catheter from a contracted state to an expanded state. The distal portion of the catheter may further comprise one or two dams (also referred to as enlarged portions, stops, bumpers, longitudinal motion preventers, or the like) and a balloon. The balloon is folded or otherwise collapsed, and is expandable to an expanded condition. The catheter further comprises a balloon protector means comprising removable first and second sleeves. The first removable (inner) sleeve is positioned over the balloon and between the dams (where two dams are present), the inner sleeve being made of a lubricious material and further comprising a first end, a second end and a slit extending therethrough. The slit may extend from end to end. Alternatively, the slit may extend along a predetermined length of the sleeve, the rest of the length of the sleeve comprising a continuous tube. The continuous tube may further comprise a dimpled region and a straight tubular region. The slit provides a variable inner diameter to ease sliding the sleeve over the balloon. The second removable (outer) sleeve is positioned over the first sleeve and dams, the outer sleeve having a constrictive relationship with the inner sleeve. The outer sleeve thereby provides an additional compressive force to reduce the profile of the collapsed balloon. For example, the outer sleeve may have an inner diameter less than the outer diameter of the inner sleeve, whereby when compressed by the outer sleeve, the inner sleeve will have an inner diameter approximately equal to or less than the outer profile of the collapsed balloon over the dam(s). The inner and outer sleeves are removed prior to use of the catheter.
Alternatively, the balloon protector may comprise a single compressive sleeve. This single compressive sleeve may be of any configuration described herein. A preferred embodiment of the single sleeve has a slit along the length thereof. Another preferred embodiment of the single sleeve has a helical slit along a predetermined length of the sleeve, defining a spiral cut region and a continuous tubular region. Yet another preferred embodiment has a spiral cut region and a continuous tubular region, the continuous tubular region comprising a dimpled region and a straight tubular region. The dimples may be round-like, spiral, triangular, oblong, longitudinal, circular (like tire treads) around the circumference or at an angle to the circumference, or combinations thereof The dimples may also be of any other suitable configuration. In another alternative embodiment, the single sleeve may comprise a dimpled region extending along part of the single sleeve or the entire sleeve.
The present invention also provides a stent delivery system including a catheter having an expandable distal portion constructed and arranged for expanding the outer diameter of the catheter from a contracted state to an expanded state. The distal portion of the catheter may further comprise one or two dams (also referred to as enlarged portions, stops, bumpers, longitudinal motion preventers, or the like) and a balloon. A stent is positioned around the distal portion of the catheter. Where there is a single dam, the stent may be positioned either proximally or distally of the dam. In an embodiment having a single proximal dam, the stent is positioned distally of the proximal dam. In an embodiment having a single distal dam, the stent is positioned proximally of the distal dam. Where two spaced dams are present, the stent is positioned between the dams, i.e. distally of the proximal dam and proximally of the distal dam. The stent has a contracted condition, being sized in the contracted condition to closely surround the balloon (the balloon in such instance being folded or otherwise collapsed), and being expandable to an expanded condition. The stent delivery system further comprises a stent protector means comprising removable first and second sleeves. The first removable (inner) sleeve is positioned around the stent and between the dams, the inner sleeve being made of a lubricious material and further comprising a first end, a second end and an expansion slit extending therethrough. The slit may extend from end to end. Alternatively, the slit may extend along a predetermined length of the sleeve, the rest of the length of the sleeve comprising a continuous tube. The continuous tube may further comprise a dimpled region and a straight tubular region. The slit provides a variable inner diameter to ease sliding the sleeve over the balloon and stent. The second removable (outer) sleeve is positioned over the stent, first sleeve and dams, the outer sleeve having a constrictive relationship with the inner sleeve. The outer sleeve thereby provides an additional compressive force to reduce the profile of the stent and collapsed balloon. For example, the outer sleeve may have an inner diameter less than the outer diameter of the inner sleeve, whereby when compressed by the outer sleeve, the inner sleeve will have an inner diameter approximately equal to or less than the outer profile of the collapsed balloon over the dam(s). The stent protector means provides reduction of the profile of the compressed stent over the collapsed balloon.
Alternatively, the stent protector means may comprise a single compressive sleeve. This single compressive sleeve may be of any configuration described herein. A preferred embodiment of the single sleeve has a slit along the length thereof. Another preferred embodiment of the single sleeve has a helical slit along a predetermined length of the sleeve, defining a spiral cut region and a continuous tubular region. Yet another preferred embodiment has a spiral cut region and a continuous tubular region, the continuous tubular region comprising a dimpled region and a straight tubular region. The dimples may be round-like, spiral, triangular, oblong, longitudinal, circular (like tire treads) around the circumference or at an angle to the circumference, or combinations thereof. The dimples may also be of any other suitable configuration. In another alternative embodiment, the single sleeve may comprise a dimpled region extending along part of the single sleeve or the entire sleeve. The sleeve(s) are removed prior to use of the stent delivery system.